Confusing Factors in the Tear Break-Up Time Test: The Influence of Contact on the Ocular Surface: Cross-Sectional Study

Abstract

Objective: The purpose of the present paper was to examine the changes in the break-up time (BUT) value of the staining procedure in the fluorescein BUT test. Material and Methods: The natural BUT values of the participants were determined with a non-invasive BUT (NI-BUT) test. Then, the changes in the tears were re-evaluated with the topographic break-up test method after the staining procedure was simulated with strips that mimicked fluorescein staining but did not contain fluorescein. The BUT test performed after the staining simulation was named sham-hybrid BUT test (SHBUT). Between the two tests, the first BUT value (BUT1st), the second BUT value (BUT2nd), the third BUT value (BUT3rd), the fourth BUT value (BUT4th), the fifth BUT value (BUT5th), and the average value of the first 3 break-ups (BUTA3) were compared. Results: Although the mean BUT1st value in NI-BUT test was found to be 4.4±2.2 seconds, it was 9.4±5.1 seconds in the SH-BUT test (p=0.000). Mean values of BUT2nd, BUT3rd, BUT4th, BUT5th and BUTA3 parameters in NI-BUT and SH-BUT tests were found to be 5.2±2.3 and 10.6±4.9 (p=0.000); 5.9±3.1 and 11.9±4.7 (p=0.000); 6.4±3.1 and 12.5±4.4 (p=0.000); 6.8±1 and 12.9±4.3 (p=0.000) and 5.2±2.4 and 10.6±4.8 seconds (p=0.000) respectively. All parameters were found to be longer in the SH-BUT test at statistically significant levels. Conclusion: The staining procedure for the fluorescein BUT test causes a prolongation of the BUT test. It is important to consider the changes in BUT because of these effects when performing the fluorescein BUT test.